Implants, methods of manufacturing the same, and devices and methods for delivering the implants to a vascular disorder of a patient

ABSTRACT

A device for delivering an implant to a vascular disorder of a patient includes a delivery pusher. A stationary blade may be coupled to the delivery pusher. The stationary blade may include a sharp and stationary cutting component for cutting through a suture coupling the implant to the delivery pusher and for thereby releasing the implant when placed in proximity to the vascular disorder. In some cases, the strength of a junction connecting the suture to the implant is equal to or greater than the tensile strength of the suture itself. Additionally, or alternatively, a detachment handle may be fixedly and permanently attached to the delivery pusher such that a user of the device need not couple the detachment handle to the delivery pusher. The detachment handle may include a user manipulable component for initiating a mechanical release of the implant when placed in proximity to the vascular disorder.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of, and incorporatesherein by reference in their entireties, U.S. Provisional PatentApplication No. 61/782,940, which was filed on Mar. 14, 2013, and U.S.Provisional Patent Application No. 61/869,265, which was filed on Aug.23, 2013.

TECHNICAL FIELD

In various embodiments, the present invention relates to devices andmethods for providing non-invasive therapy to cerebral aneurysms and/orother similar vascular disorders in which an implant (e.g., an embolicmicro-coil) is controllably delivered to a lesion and mechanicallydetached through actuation of a built-in detachment handle/cuttingmechanism. In other embodiments, the invention relates to implantableassemblies and, specifically, to a junction connecting a polymericstretch resistant member to an implantable device (e.g., an embolicmicro-coil), as well as to methods of manufacture.

BACKGROUND

A cerebral aneurysm (i.e., an acute subarachnoid hemorrhage) is acerebrovascular swelling on the wall of an artery that develops becauseof a congenitally weak cerebral artery or due to arteriosclerosis, abacterial infection, a head wound, brain syphilis, etc. The cerebralaneurysm may develop suddenly without initial symptoms, and can causeextreme pain. In general, in 15% of cerebral aneurysm cases, the patientdies suddenly upon development of the cerebral aneurysm. In another 15%of cerebral aneurysm cases, the patient dies under medical treatment;and in 30% of cerebral aneurysm cases, the patient survives aftertreatment but feels an acute aftereffect. As such, a cerebral aneurysmis a very concerning development.

A cerebral aneurysm may be treated through either an invasive therapy ora non-invasive therapy. Of these, the non-invasive therapy typicallyfills the cerebral aneurysm with a micro-coil. Generally, filling thecerebral aneurysm with the micro-coil causes blood to clot, prevents anadditional inflow of blood, and decreases the risk of a rupturedaneurysm (i.e., an embolization). Advantageously, the non-invasivetherapy can ease the aftereffects of brain surgery and can shortenhospitalization time.

The system used in the non-invasive therapy typically includes amicro-coil and a delivery pusher for carrying the micro-coil to thepatient's cerebral aneurysm. When the micro-coil is properly placed inor near the cerebral aneurysm, an operator (e.g., a physician) separatesthe micro-coil from the delivery pusher. To initiate detachment of thecoil, current micro-coil systems generally require a thermal/powersupply (for thermal or electrolytic detachment), or a mechanicaldetachment handle that is attached to the proximal end of the deliverypusher after the coil is positioned in the aneurysm.

Certain mechanical detachment systems employ the use of a core wire toremove an element that provides an interference fit between a tip of thecore wire and some component of the coil. Certain other mechanicaldetachment systems have used interlocking arms that disengage whenadvanced beyond the micro-catheter tip, or a ball-screw mechanism thatunscrews the coil from a tip of the delivery pusher when the pusher isrotated, or even hydraulic systems that eject the coil from the deliverypusher tip when the inside diameter is pressurized with saline.

Having to attach, however, a mechanical detachment handle (or some otherelement, such as a power supply box) to the proximal end of the deliverypusher after the coil is positioned in the aneurysm in order to initiatedetachment of the coil is problematic. For example, the delivery pusherand thus the coil may inadvertently move while the detachment handle (orother element) is being attached. This may cause the coil to lose itsproper placement within or near the cerebral aneurysm. In addition,attaching the detachment handle (or other element) lengthens theoperating time. Where a procedure requires many such coils to bedelivered, this can add significantly to the overall operating time.

In addition still, currently available implantable devices, such asembolic micro-coils, often employ a polymeric stretch resistant memberto maintain the shape of the micro-coil and to prevent it from unfurlingduring delivery to a patient's body. During manufacture, in order toform a mechanical securement (e.g., a junction) between the stretchresistant member and the micro-coil, the stretch resistant member isgenerally melted at, and coupled to, one or both end(s) of themicro-coil. The process of melting the polymer can, however,significantly reduce the strength of the stretch resistant member at thejunction. As such, when the micro-coil is placed under tension, themelted junction typically, and disadvantageously, fails at a force belowthe inherent tensile strength of the polymeric stretch resistant member.

Accordingly, needs exist for improved implantable assemblies and formethods of manufacturing and using the same, as well as for improvedsystems and methods for delivering the implants to a vascular disorder,such as a cerebral aneurysm.

SUMMARY OF THE INVENTION

In various embodiments, the present invention provides a mechanicalmeans of controllably detaching a micro-coil from a delivery pusher. Inparticular, embodiments of the invention conveniently provide a small,but effective, detachment handle assembly that is fixedly andpermanently attached to the proximal end of the delivery device, therebyobviating the procedural step of attaching a handle or other detachmentaccessory to the delivery pusher in order to initiate the coil'sdetachment. Such a device is easier to use, does not require anyaccessories, and simplifies the delivery procedure, particularly forthose physicians that do not perform embolization cases as often asothers.

In one embodiment, the main junction between the coil and the deliverypusher is created by a polymer suture. As such, the junction is moreflexible than the micro-coil junctions of certain prior art devices. Theflexible junction improves the ability of the coil to conform within ananeurysmal space, and also improves the safety of the medical procedureby reducing the chance for aneurysm perforation or rupture.

Additionally, embodiments of the present invention provide a mechanicalmeans for “instantaneously” detaching the micro-coil from the deliverypusher. The mechanical means includes a retractable core wire that pullsthe detachment suture through a static blade mounted to, or formedwithin, a tip of the delivery pusher. As further explained below,embodiments of the invention also feature several alternativeconfigurations of attaching the detachment suture to the delivery pusherand for severing the detachment suture from the delivery pusher.

In general, in one aspect, embodiments of the invention feature a devicefor delivering an implant, such as an embolic coil, to a vasculardisorder of a patient, such as a cerebral aneurysm. The device includesa delivery pusher (which has a proximal shaft and a flexible distalshaft) and a stationary blade that is coupled to the flexible distalshaft. The stationary blade includes a sharp and stationary cuttingcomponent for cutting through a suture that couples the implant to thedelivery pusher and for thereby releasing the implant when placed inproximity to the vascular disorder.

Various embodiments of this aspect of the invention include thefollowing features. The stationary blade may envelope an outer surfaceof the flexible distal shaft. In addition, a retractable release wiremay be positioned within a lumen of the delivery pusher. A coil hookcomponent, which may include a loop of wire, may be coupled to a distalend of the retractable release wire. In one embodiment, the sutureextends from the implant, through a portion of the delivery pusherlumen, through the wire loop of the coil hook component, and through ablunt opening in the stationary blade. In such an embodiment, as well asin other embodiments described below, the release wire, when retracted,causes the suture to be retracted towards the blade's sharp andstationary cutting component.

In addition to the blunt opening, the stationary blade may define achannel connecting the blunt opening to the sharp and stationary cuttingcomponent. Moreover, the stationary blade may further define a windowproximal to the sharp and stationary cutting component. In oneparticular embodiment, the suture coupling the implant to the deliverypusher (i) is coupled at first and second points to the retractablerelease wire positioned within the lumen of the delivery pusher, and(ii) extends through the blunt opening and the window defined by thestationary blade. In this embodiment, the device may include a secondsuture, and the suture coupling the implant to the delivery pusher maybe coupled to the implant via that second suture.

A window cutout may also be defined within a wall of the flexible distalshaft, and the blade may be positioned over the window cutout. Inaddition, a suture locking tube may be coupled to the flexible distalshaft, and a portion of the suture may be locked down between the suturelocking tube and the flexible distal shaft. Alternatively, a metal coilmay be coupled to the flexible distal shaft, and a portion of the suturemay be locked down between the metal coil and the flexible distal shaft.

In another embodiment, a polymer tip is coupled to a distal end of theflexible distal shaft. The stationary blade may be located adjacent thepolymer tip. The flexible distal shaft of the embodiments describedherein may include a flexible inner shaft, a flexible outer shaft, andan anti-elongation ribbon for preventing unwanted elongation of theflexible distal shaft.

In general, in another aspect, embodiments of the invention feature adevice for delivering an implant, such as an embolic coil, to a vasculardisorder of a patient, such as a cerebral aneurysm. The device includesa delivery pusher (which has a proximal shaft and a flexible distalshaft) and a detachment handle that includes a user manipulablecomponent for initiating a mechanical release of an implant coupled tothe delivery pusher when the implant is placed in proximity to thevascular disorder. The detachment handle may be fixedly and permanentlyattached to the proximal shaft such that a user of the device need notcouple the detachment handle to the delivery pusher.

In various embodiments, a strain relief is coupled to the detachmenthandle and also envelops a portion of the proximal shaft. In addition,the user manipulable component for initiating the mechanical release ofthe implant may include a handle slider.

In general, in yet another aspect, embodiments of the invention featurea method for delivering an implant, such as an embolic coil, to avascular disorder of a patient, such as a cerebral aneurysm. Inaccordance with the method, the implant (which is coupled via a sutureto a delivery pusher) is advanced in proximity to the vascular disorder.The delivery pusher, which may be used in that regard, includes astationary blade, which itself includes a sharp and stationary cuttingcomponent. The suture is then caused to impinge upon the sharp andstationary cutting component, which cuts through the suture. The implantis thereby released in proximity to the vascular disorder.

Again, the stationary blade may envelope an outer surface of thedelivery pusher. In addition, the suture may be caused to impinge uponthe sharp and stationary cutting component by retracting a release wirecoupled to the suture.

In general, in still another aspect, embodiments of the inventionfeature a method for delivering an implant, such as an embolic coil, toa vascular disorder of a patient, such as a cerebral aneurysm. Inaccordance with the method, the implant (which is coupled to a deliverypusher) is advanced in proximity to the vascular disorder. The deliverypusher, which may be used in that regard, is fixedly and permanentlyattached to a detachment handle such that a user need not couple thedetachment handle to the delivery pusher. The detachment handle includesa user manipulable component, such as a handle slider, which is actuatedto initiate a mechanical release of the implant from the deliverypusher.

In certain other embodiments, the present invention relates to a systemthat increases the strength of a junction connecting a polymeric stretchresistant member to an implantable device (e.g., an embolic micro-coil)to be equal to or greater than the tensile strength of the stretchresistant member itself, as well as to methods of manufacturing andusing the same. In one embodiment, the objective is accomplished withoutany additional materials or adhesives being employed, therebysimplifying the manufacturing process. The stretch resistant member may,for example, be permanently attached to the micro-coil and be eventuallyimplanted within a patient's body together with the micro-coil. As such,the regulatory acceptance of such an implantable assembly can besimplified.

In one embodiment of the invention, the polymeric stretch resistantmember includes two components. One component maximizes the attachmentstrength to the micro-coil and the other component provides stretchresistance for the micro-coil and attachment to a delivery pusher.

In general, in one aspect, embodiments of the invention feature animplantable assembly. The implantable assembly includes an implantabledevice and a stretch resistant member. The implantable device (e.g., acoil) includes a proximal end and a distal end and defines a passagewaythat extends from the proximal end to the distal end, while the stretchresistant member extends along the passageway and is coupled to thedistal end at a junction. The stretch resistant member includes firstand second components. The second component, which is different from andcoupled to the first component, includes multiple strands coupled to thejunction and with a coupling strength greater than a tensile strength ofthe first component.

In various embodiments, the stretch resistant member is coupled to theimplantable device at only the distal end. The stretch resistant membermay also be coupled to a delivery pusher. The stretch resistant membermay include a polymeric material, such as polypropylene. In oneembodiment, the first component of the stretch resistant member includesa knot at a distal end thereof. The second component may be knottedaround the first component at a point proximal to the knot of the firstcomponent.

The multiple strands of the second component (e.g., four strand ends)may extend from the point proximal to the knot of the first componenttoward the distal end of the implantable device. The multiple strandsmay also be molded to the distal end to form the junction, which may bean atraumatic tip, such as a ball tip.

In general, in another aspect, embodiments of the invention feature amethod of manufacturing an implantable assembly. The method includes thesteps of coupling a first component of a stretch resistant member to asecond component of the stretch resistant member, and extending thestretch resistant member through a passageway defined by an implantabledevice, such as a coil. The first and second components may be differentfrom one another, the second component may include multiple strands, andthe implantable device may include a proximal end and a distal end. Themethod further includes the step of coupling the multiple strands of thesecond component to the distal end of the implantable device at ajunction and with a coupling strength greater than a tensile strength ofthe first component.

In various embodiments of this aspect of the invention, the stretchresistant member includes a polymeric material, such as polypropylene.Coupling the first component to the second component may be accomplishedby forming a knot at a distal end of the first component, and thenknotting the second component around the first component at a pointproximal to the knot of the first component. The multiple strands of thesecond component (e.g., four strand ends) may be extended from the pointproximal to the knot of the first component toward the distal end of theimplantable device.

Coupling the multiple strands of the second component to the distal endof the implantable device may be accomplished by melting distal ends ofthe multiple strands and molding the melted distal ends to the distalend of the implantable device to form the junction. The junction mayinclude an atraumatic tip, such as a tip ball.

The above-described method may also include the step of coupling thestretch resistant member to a delivery pusher.

These and other objects, along with advantages and features of theembodiments of the present invention herein disclosed, will become moreapparent through reference to the following description, theaccompanying drawings, and the claims. Furthermore, it is to beunderstood that the features of the various embodiments described hereinare not mutually exclusive and can exist in various combinations andpermutations.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings, like reference characters generally refer to the sameparts throughout the different views. Also, the drawings are notnecessarily to scale, emphasis instead generally being placed uponillustrating the principles of the invention. In the followingdescription, various embodiments of the present invention are describedwith reference to the following drawings, in which:

FIG. 1 schematically illustrates various components at a distal portionof a delivery device in accordance with one embodiment of the invention;

FIG. 2 schematically illustrates a portion of the delivery device'sdelivery pusher in accordance with one embodiment of the invention;

FIG. 3 schematically illustrates another portion of the deliverydevice's delivery pusher in accordance with one embodiment of theinvention;

FIG. 4 schematically illustrates yet another portion of the deliverydevice's delivery pusher in accordance with one embodiment of theinvention;

FIG. 5 schematically illustrates still another portion of the deliverydevice's delivery pusher in accordance with one embodiment of theinvention;

FIG. 6 schematically illustrates various components at a proximalportion of the delivery device, including a detachment handle, inaccordance with one embodiment of the invention;

FIG. 7A schematically illustrates a side view of a single sutureconfiguration of an embolic coil in accordance with one embodiment ofthe invention;

FIG. 7B schematically illustrates a cross-sectional view of the singlesuture configuration of the embolic coil in accordance with oneembodiment of the invention;

FIG. 8A schematically illustrates a side view of the single sutureconfiguration of the embolic coil, heat set into a secondary coil shape,in accordance with one embodiment of the invention;

FIG. 8B schematically illustrates a front view of the single sutureconfiguration of the embolic coil, heat set into the secondary coilshape, in accordance with one embodiment of the invention;

FIG. 9A schematically illustrates a side view of a double sutureconfiguration of an embolic coil in accordance with one embodiment ofthe invention;

FIG. 9B schematically illustrates a cross-sectional view of the doublesuture configuration of the embolic coil in accordance with oneembodiment of the invention;

FIG. 10A schematically illustrates a side view of the double sutureconfiguration of the embolic coil, heat set into a secondary coil shape,in accordance with one embodiment of the invention;

FIG. 10B schematically illustrates a front view of the double sutureconfiguration of the embolic coil, heat set into the secondary coilshape, in accordance with one embodiment of the invention;

FIG. 11 schematically illustrates a series of steps for releasing anembolic coil from a delivery device in accordance with one embodiment ofthe invention;

FIGS. 12-14 schematically illustrate various alternative embodiments forattaching a micro-coil to a delivery pusher in accordance with theinvention;

FIGS. 15-17 schematically illustrate various embodiments of a coil hookin accordance with the invention;

FIGS. 18-28 schematically illustrate various embodiments of blades forsevering a suture in accordance with the invention;

FIG. 29 schematically illustrates a polymeric stretch resistant memberin accordance with one embodiment of the invention; and

FIGS. 30A-30B schematically illustrate the individual steps in a methodof manufacturing an implantable assembly in accordance with oneembodiment of the invention.

DESCRIPTION

In broad overview, embodiments of the present invention feature a devicefor delivering an implant (e.g., an embolic coil) to a vascular disorderof a patient, such as a cerebral aneurysm. The overall delivery device100 is shown at the bottom of each of FIGS. 1-6. In addition, in each ofFIGS. 1-6, a portion of the overall delivery device 100 is delineated inphantom, and that delineated portion is depicted in greater detail abovethe depiction of the overall delivery device 100.

As shown in FIG. 1, an embolic coil 104 is attached to a delivery pusher108 of the delivery device 100. The delivery pusher 108 contains, withina lumen thereof, a retractable release wire 112. As shown in FIGS.7A-10B, in one embodiment the embolic coil 104 includes a primary coil(see FIGS. 7A-7B and 9A-9B) wound from metallic wire (preferablyPlatinum 8% Tungsten) that is heat set into a secondary coil shape (seeFIGS. 8A-8B and 10A-10B). The embolic coil 104 is made stretch resistantby melting a ball 704 of polymer (preferably monofilament polypropylene)suture 708 at a distal end 712 of the coil 104 and threading the suture708 through a proximal end 716 of the primary coil 104. The suture 708is preferably sized so as to have a United States Pharmacopeia (“USP”)9-0 suture designation, which means that the suture 708 typically has adiameter between 0.0012″ and 0.0017″. In other configurations, however,the suture 708 may be smaller or larger and/or be made of otherpolymers. As shown in FIGS. 9A-9B and 10A-10B, the suture 708 may bedoubled through the inside diameter of the primary coil or, as shown inFIGS. 7A-7B and 8A-8B, only a single strand of the suture 708 may extendthrough the primary coil. The termination of the double sutureconfiguration can be a knot 904 created between the two strands withinthe inside diameter of the primary coil. In either the single or doublesuture configuration, the preferred design is to have only a singlestrand exiting the primary coil inside diameter into the delivery pusher108 as it is desirable to only sever a single strand during detachmentactuation. Alternate designs for connecting the coil to the deliverypusher are discussed further below.

The delivery pusher 108 includes a proximal shaft 304 (see FIGS. 3-6)and a flexible distal shaft 116 (see FIGS. 1-3). The proximal shaft 304may be made from rigid, metal hypotube, preferably 300 series stainlesssteel with a wall thickness of about 0.002″ to provide good pushabilityduring coil 104 delivery and stability during detachment actuation. Theflexible distal shaft 116 includes a flexible inner shaft 120 made froma rigid thin-walled polymer (preferably PEEK with a wall thickness ofabout 0.001″), a flexible outer shaft 204 made from a rigid thin-walledpolymer (preferably PEEK with a wall thickness of about 0.001″), and ananti-elongation component 208 (made preferably from 300 series stainlesssteel ribbon).

As shown in FIG. 1, a stationary blade 124 (preferably 300 seriesstainless steel) may be attached to a distal end 128 of the flexibleinner shaft 120 with an adhesive. The blade 124 may be located behind apolymer delivery pusher tip 132 (preferably pebax-polyether blockamide), which is intended to provide an atraumatic interface and helpsecure the blade 124 to the flexible inner shaft 120. The flexible innershaft 120 has a window cutout 136 at the distal end 128 thereof thatallows the suture 708 to move within the laser-cut geometry of the bladeduring detachment. This window 136 may be hand cut, machine cut, ground,or laser cut. Located proximal to the blade 124 is a suture locking tube140, which is a short length of polymer (preferably heat-shrinkpolyethylene terephthalate (PET)) that helps lock down the detachmentsuture 708 to the flexible inner shaft 120.

With reference still to FIG. 1, located inside the delivery pusher 108is the retractable release wire 112. The retractable release wire 112includes a core wire (preferably 300 series stainless steel), which isground on the distal end, is between 35 cm to 75 cm (preferably about 60cm) in length, and is coated on the unground section with, for example,polytetrafluoroethylene (PTFE) to reduce friction. Preferably, the corewire is about 0.006″ in diameter, and ground to about 0.002″ at the tip.A coil hook component 144, preferably made from 300 series stainlesssteel with about 0.001″ diameter wire, may be created by winding asegment of wire into a short coil of about 1 mm and a short “hook” andsoldering these components in the shape shown in FIG. 1 to the tip ofthe retractable release wire 112.

As also shown in FIG. 1, the detachment suture 708 extends from theprimary coil 104, is threaded through an inside diameter of the deliverypusher 108 tip 132, through the loop of the coil hook 144, and through afront opening 148 of the attached blade 124, is aligned with a notch 152(see also FIG. 18) in the proximal end of the blade 124, and is attachedto the flexible inner shaft 120 by the suture locking tube 140.Additionally, the proximal end of the suture 708 may be tied into a knot156 around the flexible inner shaft 120 and adhesive may be applied tothe knot 156, or the knot 156 may be slightly melted to further securethe suture 708 in position.

With reference now to FIG. 6, the proximal shaft 304 is connected to ahandle body 604 of a detachment handle 600 by inserting the proximalshaft 304 into a cavity in the injection molded handle body 604 and byapplying adhesive or press fitting the connection. As such, followingmanufacture, the detachment handle 600 is fixedly and permanentlyattached to the proximal shaft 304 such that a user of the device (e.g.,a physician) need not himself or herself couple the detachment handle600 to the delivery pusher 108 for any reason, including to initiatedetachment of the micro-coil 104 from the delivery pusher 108. As alsoshown in FIG. 6, a strain relief 608 (preferably made from pebax) may beemployed to help prevent kinking at the junction of the proximal shaft304 and handle body 604.

The handle body 604 may include one or more injection molded parts,preferably made from acrylonitrile butadiene styrene (ABS). A proximalend of the retractable release wire 112 may be secured to a handleslider 612 of the detachment handle 600, for example by threading thewire 112 through a channel in the handle slider 612 and bending the wire112 to form a mechanical hook bond within the handle slider 612.Adhesive may also be applied to secure these two components together.Upon manufacturing the delivery device 100, the handle body 604 andhandle slider 612 may be assembled in a “locked” position, in which theretractable release wire 112 and coil hook 144 are locked in positionrelative to the blade 124. These parts may be held in place by detentfeatures molded into the handle body 604 and handle slider 612 matingsurfaces.

In other embodiments, rather than featuring the handle slider 612, thedetachment handle 600 may instead feature another user manipulablecomponent for initiating the mechanical release, as described herein, ofthe embolic coil 104. For example, the detachment handle 600 may featurea mechanical trigger, a mechanical push-button, or other mechanicalcomponent that requires mechanical input from a user of the device(e.g., a physician) in order to initiate the mechanical detachment ofthe embolic coil 104.

FIGS. 4 and 5 show an introducer sheath 400, which protects themicro-coil 104 during sterilization and shipment, and a proximal lockingtube 500, which locks the introducer sheath 400 in place on the proximalshaft 304. FIG. 5 also shows proximal shaft markings 504, whichpreferably are laser-etched into the proximal shaft 304 hypotube. Thefunction of these markings 504 is to designate to the user, duringintroduction of the micro-coil 104 into a micro-catheter, the positionof the micro-coil 104 relative to the micro-catheter tip to savefluoroscopy time and to reduce unnecessary x-ray radiation to thepatient.

FIG. 11 depicts the manner by which the suture 708 may be severed so asto release the micro-coil 104 from the delivery pusher 108. Thedetachment handle 600 is intended to be held by the user like a syringe,with thumb placed on a proximal end of the handle 600 and index andmiddle fingers straddling the handle body 604 with the index and middlefingertips placed on either side of the handle slider 612. Since thesuture strand 708 extending from the embolic micro-coil 104 is threadedthrough the coil hook 144, which is attached to the retractable releasewire 112, when the release wire 112 is retracted (by retraction of thehandle slider 612), the coil hook 144 pulls the suture 708 through anopen channel 1104 of the blade 124 and into a sharp section 1108 of theblade 124 (i.e., a sharp and stationary cutting component 1108), therebysevering the suture 708 and releasing the coil 104 from the deliverypusher 108 tip 132. In this preferred configuration, there is a slightgap between the proximal end 716 of the micro-coil 104 and the deliverypusher 108 tip 132. During detachment, the micro-coil 104 tends to movebackward slightly, but the diameter of the proximal end 716 of themicro-coil 104 is nearly identical to the diameter of the deliver pusher108 tip 132. This configuration allows the proximal end 716 of themicro-coil 104 to contact the surface of the delivery pusher 108 tip132, but prevents the micro-coil 104 from entering the inside diameterof the delivery pusher 108 tip 132. After the suture 708 is severed, theslight compressive force that exists between the proximal end 716 of themicro-coil 104 and the delivery pusher 108 tip 132 tends to nudge themicro-coil 104 away from the delivery pusher 108 tip 132.

As shown in FIG. 2, an anti-elongation ribbon 208 is employed to preventthe coil 104 from prematurely (and thus undesirably) detaching from thedelivery pusher 108 prior to detachment actuation. In particular,although the flexible distal shaft 116 utilizes rigid polymer members(for stability during mechanical detachment), it also needs to provideenough flexibility and low-friction to access the neurovasculaturethrough a micro-catheter. As such, the flexible distal shaft 116 is moresusceptible to elongation than the metal proximal shaft 304 or theretractable release wire 112. Since the flexible distal shaft116/proximal shaft 304 assembly and the retractable release wire 112 areconnected at the proximal end of the delivery pusher 108, within theproximal detachment handle 600, if the delivery device 100 encountersfriction during delivery the proximal shaft 304 and retractable releasewire 112 will likely retract at the same rate, but the flexible distalshaft 116 will elongate at a greater rate. If the flexible distal shaft116 elongates at a greater rate than the retractable release wire 112and proximal shaft 304, in effect the coil hook 144 will pull thedetachment suture 708 into the blade 124, severing the suture 708 andprematurely detaching the coil 104 from the delivery pusher 108. Toprevent this from happening, the anti-elongation ribbon 208 is attachedbetween (and to both of) the flexible distal shaft 116 and a radiopaquemarker 212, which is itself attached to the outside of the flexibledistal shaft 116, by use of an adhesive or solder or both. Theanti-elongation ribbon 208 prevents unwanted elongation of the flexibledistal shaft 116 during retraction of the delivery pusher 108 inside themicro-catheter.

Several laser-cut blade 124 iterations have been developed for variousperformance advantages. In the preferred design illustrated in FIGS. 1and 18, the large round opening 148 in the distal part of the blade 124allows for easy insertion of the suture 708 from the end hole of thedelivery pusher 108 during manufacturing. The width of the laser-cut,angled “neck” or channel 160 of the blade 124 is slightly smaller thanthe suture 708 thickness to help prevent the suture 708 frominadvertently sliding backward into the straight portion 164 of thelaser-cut channel. The angle of the neck 160 is also intended to helpprevent inadvertent suture 708 movement into the straight channel 164during normal use of the micro-coil 104/delivery pusher 108 system. Thestraight portion 164 of the laser-cut channel is preferably equal to orslightly wider than the suture 708 diameter to allow quick, unrestrictedmovement of the suture 708 through the channel 164 into the sharpportion 1108 of the blade during detachment actuation. The length of thestraight portion 164 of the laser-cut channel also allows theretractable release wire 112 to move backward slightly, relative to theflexible distal shaft 116 during normal advancement and retraction ofthe delivery pusher 108, subject to frictional forces between thedelivery pusher 108 and the micro-catheter. A minimum length in thisstraight portion 164 of the channel, therefore, provides additionalsafety and prevention against inadvertent suture 708 movement andpremature detachment.

As explained below, the portion 1108 of the blade 124 that is intendedto sever and cut the suture 708 has several features that optimizecutting. Optimization of cutting is generally employed herein to meanminimizing the force required to cut the suture 708 in the blade 124.The advantages of minimizing the cut force include reducing movement ofthe delivery pusher 108 tip 132 and coil 104 during detachment, andcreating a gentler separation of the micro-coil 104 from the deliverypusher 108.

Cut force minimization has been achieved by creating a blade geometrythat increases the slice-push ratio. Slicing requires that the blade bedisplaced with some velocity parallel to the cutting edge, while pushing(or chopping) requires that the blade be displaced with some velocityperpendicular to the cutting edge. It is well known in thescience/engineering of cutting materials that slicing, or cutting inmore of a sideways motion, is easier (and requires less force) than doeschopping at a right angle to the material. In other words, slicingrequires less energy to cut through a given cross section of materialthan does chopping, which has the maximum normal force of the blade edgeto the cross section to be cut.

In one embodiment, as illustrated in FIG. 18, the blade 124 geometry forcutting the suture 708 has the following features in the sharp section1108 of the blade 124:

-   -   1) a converging V-shape, which has at least one sharp edge, and        converges the suture 708 to progressively become smaller in        cross section as it is pulled backward through the V-shape;    -   2) a tooth or edge 1804 on the sharp side or both sides of the        V-shape, near the entrance of the V-shape, to initiate a cut or        cuts in the side of the suture 708;    -   3) a length of the V-shape that is long enough to slice through        the suture 708 cross section (if the V-shape is too short or        shallow, then this essentially chops the suture 708, which        increases the cut force); and    -   4) a thinning out of the wall of the blade 124 in the sharp        section 1108, again to reduce the force required to force the        suture 708 through the V-shape (less surface area of the blade        124 dragging on the suture 708 will equate to less force).

Various other blade 124 geometries that have some of the elementsdescribed above in order to cut the suture 708 with low force have alsobeen prototyped. These are shown in FIGS. 19-28. Blade 124 designs C(FIG. 19), V (FIG. 20), and CV (FIG. 21) have sharp edges of variousgeometries, but generally are shorter than desirable. If the edge ismade thin enough (and sharp enough) it can still cut efficiently. Blade124 design CV Extended (FIG. 22) features a longer straight channel thatallows increased velocity in pulling the suture 708 backward. The Peanut(FIG. 23) and V-Returns (FIG. 24) blade 124 designs have longer straightchannels for increased velocity and also converging edges to cut moreefficiently. The Snake (FIG. 25) blade 124 design forces the suture 708to be pulled through twisting edges, making cuts on either side of thesuture 708, but may increase the normal forces depending on the angle ofthe snake pattern. Also, the Peanut (FIG. 23), V-Returns (FIG. 24), andSnake (FIG. 25) blades 124 have a bottom half of a distal end of theblade 124 removed, which is an alternative approach that may be used tomake the delivery pusher 108 tip 132 softer (through the absence of thismaterial).

FIG. 26 shows a Seahorse design for the blade 124, which has elements ofthe preferred design (i.e., the V-scythe design depicted in FIG. 18) andalso a proximal window 2604 to allow for the coil suture 1404/detachsuture 1408 configuration shown in FIG. 14 and discussed below. The Banddesign for the blade 124 depicted in FIG. 27 essentially features onlythe sharp section 1108 of the blade 124, which is the portion thatactually cuts the suture 708, thereby allowing the entire blade 124length to be shortened. Using this design typically requires that theflexible inner shaft 120 have the features in the omitted portion of theblade 124 (e.g., the large round opening 148 to thread the suture 708through, the angled neck 160, and the straight channel 164). However,this alternative can make the delivery pusher 108 tip 132 softer andmore flexible. The Scythe design of the blade 124 depicted in FIG. 20has almost all the same elements as the V-scythe design depicted in FIG.18, but the sharp portion 1108 terminates into a round edge 2804, whichis intended to provide a final cut to whatever small cross section ofsuture 708 may remain after being pulled through the skinny sharpchannel 2808 of the sharp portion 1108.

Various other designs for attaching the micro-coil 104 to the deliverypusher 108 are depicted in FIGS. 12-14. In particular, FIG. 12 shows analternate way of attaching the detachment suture 708 to the deliverypusher 108 by threading the suture 708 underneath a metal coil 1204(preferably 300 series stainless steel) that is proximal to the blade124, instead of using the heat-shrink tubing 140. Adhesive may beapplied to the metal coil 1204 and suture 708 to secure both componentstogether.

FIG. 13 shows an alternative way for connecting the micro-coil 104 tothe delivery pusher 108 by threading a double suture 708 configurationwithin the inside diameter of the primary (e.g., platinum) coil 104 andcreating a suture loop 1304 that protrudes from the proximal end 716 ofthe primary coil 104. In this embodiment, the manufacturing procedure ismodified to loop the suture 708 through the inside of the end hole 1308of the delivery pusher 108, through the opening in the flexible innershaft 120, through the front opening 148 of the blade 124, and then backthrough the inside diameter of the primary coil 104. One advantage ofthis design is that it obviates the need to attach the suture 708 to thedelivery pusher 108, thereby simplifying this portion of themanufacturing process.

FIG. 14 shows yet another micro-coil 104 attachment configuration thatuses a double-suture on the inside diameter of the micro-coil (“coilsuture 1404”) and a separate suture (“detach suture 1408”). The detachsuture 1408 may be made of the same material as the coil suture 1404 orof other polymer material suitable for cutting. In this configuration,the retractable release wire 112 has two “stopper” coils 1412, 1416attached to the tip of the core wire, by solder or adhesive, with asmall space between them. These coils 1412, 1416 may be made of a metalsuch as 300 series stainless steel or platinum alloy. The detach suture1408 is first connected to the retractable release wire 112 behind thefront stopper coil 1412, for example by tying a knot and applyingadhesive or melting it slightly. The detach suture 1408 is then loopedthrough the coil suture loop 1404 and pushed through the top frontopening 148 of the blade 124 and then through the proximal window 2604of the blade 124. This end of the detach suture 1408 is then connectedto the retractable release wire 112 behind the proximal stopper coil1416, for example by using a method similar to the first detach suture1408 connection. The purpose of the proximal window 2604 is to allow anassembler to attach the detach suture 1408 behind the proximal stoppercoil 1416. Instead of having the proximal window 2604 in the blade 124(which increases the total blade 124 length), the window 2604 mayalternatively be placed in the flexible inner shaft 120, behind theblade 124.

Various configurations of the coil hook 144 are shown in FIGS. 15-17. Inparticular, FIG. 15 shows a simplified design of a hook 144 that may beused to pull the suture 708 through the blade 124 for detachment. Thishook 144 is created by bending the ground core wire (i.e., the tip ofthe retractable release wire 112) into a hook shape and securing thewire 112 to itself by means of, for example, soldering, welding, and/oradhesive. In some embodiments, bending this core wire in this manneralso requires annealing or heat treatment to properly form the hookshape. The advantage of this design is that the dimensional profile ofthe hook 144 is smaller than if there were separate coil hookcomponents. Also, since there are fewer components, the manufacturingprocess is simplified.

FIG. 16 shows a configuration in which the coil hook 144 is created bybending a single strand of wire into a coil shape 1604 and then into ahook shape 1608. The end of the hook 1608 may be tucked inside the coil1604 between the coil 1604 and the core wire 112, and attached in amanner similar to the previously described preferred configuration.

FIG. 17 shows a combination of the two designs depicted in FIGS. 15 and16 in which the coil hook 144 is formed as described in FIG. 15, and acoil 1704 is then placed over the ends of the formed core wire 112 tofurther secure the core wire 112 to itself. The coil 1704 may beattached by, for example, means of soldering, welding, and/or adhesive.

In operation, the micro-coil 104 may be introduced, delivered,positioned, and implanted at the desired site within the vasculatureusing a micro-catheter. In particular, in treating neurovascular orperipheral vascular conditions requiring embolization, the sites may befirst accessed by the micro-catheter, which is a flexible, smalldiameter catheter (typically with an inside diameter between 0.016″ to0.021″), through an introducer sheath/guiding catheter combination thatis placed in the femoral artery or groin area of the patient. Themicro-catheter may be guided to the site through the use of guidewires.Guidewires typically comprise long, torqueable proximal wire sectionswith more flexible distal wire sections designed to be advanced withintortuous vessels. A guidewire is visible using fluoroscopy and istypically used to first access the desired site, thereby allowing themicro-catheter to be advanced over it to the desired site.

In one embodiment, once the desired site has been accessed with themicro-catheter tip, the catheter lumen is cleared by removing theguidewire, and the micro-coil 104 is placed into the proximal open endof the micro-catheter and advanced by its delivery pusher 108 throughthe micro-catheter. When the micro-coil 104 reaches the distal end ofthe micro-catheter, it is deployed from the micro-catheter andpositioned by the delivery pusher 108 into the vascular site. The user(e.g., a physician) may advance and retract the micro-coil 104 severaltimes to obtain a desirable position of the micro-coil 104 within thelesion. Once the micro-coil 104 is satisfactorily positioned within thelesion, the detachment handle 600 is employed to mechanically releasethe micro-coil 104 into the lesion, as described above. Then, oncedetachment of the micro-coil 104 has been confirmed, the detachmenthandle 600 and delivery pusher 108 are removed from the micro-catheter,and additional micro-coils 104 may be placed in the same manner, asnecessary for proper treatment.

In other embodiments, the present invention features an implantableassembly. The implantable assembly includes an implantable device and apolymeric stretch resistant member. The implantable device may, asillustrated in FIGS. 7A-10B, be a coil 104 (e.g., a micro-coil) thatincludes a proximal end 716 and a distal end 712 and that defines apassageway 720 (see FIGS. 7B and 9B), for example a lumen, extendingfrom the proximal end 716 to the distal end 712. The polymeric stretchresistant member 2900 (see FIG. 29), for example a polypropylenefilament, may extend along the passageway 720 and be coupled to thedistal end 712 at a junction.

In one embodiment of the present invention, the stretch resistant member2900 is formed of two components. The first component can be a single,double, or even triple or quadruple stranded stretch resistant materialthat has a knot formed at a distal end thereof. The second component,which typically is a discrete component (i.e., is different from thefirst component), may include the same stretch resistant material as thefirst component and may be knotted around the first component at a pointproximal to the knot of the first component. This attachment initiallyallows the two components to slide relative to one another during themanufacturing process, but that need not be a feature of the finalassembly. The second component may include one, two, or more strands ofthe stretch resistant material, which are pulled toward the distal endof the micro-coil 104 and whose ends may be melted and molded into thewinds of the micro-coil 104 to form an atraumatic round tip 2904, suchas a tip ball. FIG. 29 depicts an exemplary embodiment of the finalsystem, but without the micro-coil 104 present, so that the detail ofthe stretch resistant member 2900 is visible.

In one embodiment, and as described in further detail below, the secondcomponent of the stretch resistant member includes two strands, and fourstrand ends (i.e., each end of the two strands) are melted to from thejunction (e.g., the tip ball 2904), thereby increasing the overallattachment strength to the melted tip ball 2904. In addition, the lengthof the strands between the melted tip ball 2904 and the knot-to-knotconnection between the two components of the stretch resistant member2900 prevents the stretch resistant member's first component from beingaffected by heat during the process of forming the melted tip ball 2904.Advantageously, these features result in the strands of the secondcomponent being coupled to the melted tip ball 2904 with a couplingstrength greater than a tensile strength of the first component, andthereby avoid a typical failure seen in prior approaches—i.e., a “heataffected” zone of the stretch resistant member (i.e., the portion of thestretch resistant member that enters the melted tip ball) pulling awayfrom and breaking at the melted tip ball when the micro-coil is placedunder tension. This tensile failure of prior approaches typically occursat a tensile load that is significantly lower than the original tensilestrength of the stretch resistant member, presumably due to an effectfrom the process of forming the melted tip ball.

The knot-to-knot connection between the two components of the stretchresistant member 2900 also allows for four strand ends to transition toa single or double strand of suture, which runs through the entirelength of the micro-coil 104, providing the desired feature of stretchresistance. This configuration also allows flexibility in componentselection, such that a larger diameter suture may be used for the firstcomponent of the stretch resistant member 2900.

In one embodiment, a preferred material for the stretch resistant member2900 is a monofilament polypropylene suture, in a size of 9-0 (whichtypically has a diameter between 0.0012″ and 0.0017″), but the suturemay be smaller or larger and/or made from other polymers in otherconfigurations depending on, for example, the inside diameter of themicro-coil 104 component.

As illustrated in FIGS. 7A-10B, and as described earlier, the micro-coil104 may include a primary coil that is wound from metallic wire (e.g.,Platinum 8% Tungsten) and that is then heat set into a secondary shape,such as a complex “3D” shape suitable for “framing” an aneurysm, such asa cerebral aneurysm, or a simple helical shape suitable for “filling”and/or “finishing”.

FIGS. 30A-30B depict the individual steps in a method of manufacturingthe implantable assembly, according to one exemplary embodiment of theinvention. As illustrated, a single strand of suture 3004 (i.e., thefirst component 3004 of the stretch resistant member 2900) is firstlooped (Step 1), and an end of the loop is then routed to form a knot3008 near the end of the loop (Step 2, 3 and 4), which may optionally becut or cut off at this point. Next, two separate strands 3012 of sutureof substantially equal length (i.e., the second component 3012 of thestretch resistant member 2900) are knotted around a proximal end of thefirst suture 3004 (Steps 5, 6 and 7) such that approximately equallengths of the suture ends 3016 remain on either side. The ends 3016 ofthe second suture strands 3012 are then pulled such that the second knot3020 is tight around the first suture component 3004 and against theknot 3008 of the first component 3004, and then the second suturestrands 3012 are pulled toward the distal end of the subassembly 2900,past the knot 3008 of the first component 3004 (Step 8). The loop of thefirst component 3004 can also be cut or trimmed to a desired length atthis point (Step 8). The second suture ends 3016 are also trimmed to acertain suture length (e.g., to a length of 2 mm) and the subassembly2900 is then inserted into the micro-coil 104 (Step 9). Finally, thesecond suture ends 3016 are melted, typically through a conductivesource such as a soldering iron or a heated rod, and molded into thewinds of the micro-coil 104 to form an atraumatic tip 2904 (e.g., around tip ball 2904) at the distal end 712 of the micro-coil 104 (Step10). In one particular embodiment, the stretch resistant member 2900 is,as described, coupled to the micro-coil 104 at only the distal end 712thereof.

In practice, the tensile strength of the stretch resistant member'sfirst component 3004 may be in a range of about 60,000 pounds per squareinch (psi) to about 90,000 psi and, by employing the afore-describedassembly, the strands of the stretch resistant member's second component3012 may be coupled to the distal end 712 of the micro-coil 104 at ajunction 2904 and with a coupling strength greater than that tensilestrength of the first component 3004, for example in a range of about120,000 psi to about 150,000 psi or more.

Having described certain embodiments of the invention, it will beapparent to those of ordinary skill in the art that other embodimentsincorporating the concepts disclosed herein may be used withoutdeparting from the spirit and scope of the invention. Accordingly, thedescribed embodiments are to be considered in all respects as onlyillustrative and not restrictive.

What is claimed is:
 1. An implantable assembly, comprising: animplantable device comprising a proximal end and a distal end anddefining a passageway extending from the proximal end to the distal end;and a stretch resistant member extending along the passageway andcoupled to the distal end at a junction, the stretch resistant membercomprising a first component and a second component different from andcoupled to the first component, the second component comprising aplurality of strands coupled to the junction and with a couplingstrength greater than a tensile strength of the first component.
 2. Theimplantable assembly of claim 1, wherein the implantable devicecomprises a coil.
 3. The implantable assembly of claim 1, wherein thestretch resistant member is coupled to the implantable device at onlythe distal end.
 4. The implantable assembly of claim 1, wherein thestretch resistant member is further coupled to a delivery pusher.
 5. Theimplantable assembly of claim 1, wherein the stretch resistant membercomprises a polymeric material.
 6. The implantable assembly of claim 5,wherein the polymeric material comprises polypropylene.
 7. Theimplantable assembly of claim 1, wherein the first component of thestretch resistant member comprises a knot at a distal end thereof. 8.The implantable assembly of claim 7, wherein the second component isknotted around the first component at a point proximal to the knot ofthe first component.
 9. The implantable assembly of claim 8, wherein theplurality of strands of the second component extend from the pointproximal to the knot of the first component toward the distal end of theimplantable device.
 10. The implantable assembly of claim 9, wherein thesecond component comprises four strand ends that extend from the pointproximal to the knot of the first component toward the distal end of theimplantable device.
 11. The implantable assembly of claim 1, wherein theplurality of strands of the second component are molded to the distalend to form the junction.
 12. The implantable assembly of claim 1,wherein the junction comprises an atraumatic tip.
 13. The implantableassembly of claim 1, wherein the junction comprises a tip ball.
 14. Amethod of manufacturing an implantable assembly, the method comprisingthe steps of: coupling a first component of a stretch resistant memberto a second component of the stretch resistant member, the first andsecond components being different from one another, and the secondcomponent comprising a plurality of strands; extending the stretchresistant member through a passageway defined by an implantable device,the implantable device comprising a proximal end and a distal end; andcoupling the plurality of strands of the second component to the distalend at a junction and with a coupling strength greater than a tensilestrength of the first component.
 15. The method of claim 14, wherein theimplantable device comprises a coil.
 16. The method of claim 14, whereinthe stretch resistant member comprises a polymeric material.
 17. Themethod of claim 16, wherein the polymeric material comprisespolypropylene.
 18. The method of claim 14, wherein coupling the firstcomponent to the second component comprises forming a knot at a distalend of the first component.
 19. The method of claim 18, wherein couplingthe first component to the second component further comprises knottingthe second component around the first component at a point proximal tothe knot of the first component.
 20. The method of claim 19 furthercomprising extending the plurality of strands of the second componentfrom the point proximal to the knot of the first component toward thedistal end of the implantable device.
 21. The method of claim 20,wherein the second component comprises four strand ends that areextended from the point proximal to the knot of the first componenttoward the distal end of the implantable device.
 22. The method of claim14, wherein coupling the plurality of strands of the second componentcomprises melting distal ends of the plurality of strands.
 23. Themethod of claim 22, wherein coupling the plurality of strands of thesecond component further comprises molding the melted distal ends of theplurality of strands to the distal end of the implantable device to formthe junction.
 24. The method of claim 14, wherein the junction comprisesan atraumatic tip.
 25. The method of claim 14, wherein the junctioncomprises a tip ball.
 26. The method of claim 14 further comprisingcoupling the stretch resistant member to a delivery pusher.